But it is not clear that boat people really had much effect on the election result. When the Tampa arrived, the Howard government had already been steadily improving its opinion poll position from the early 2001 nadir. Tampa and, later, “children overboard” melted the talkback lines, but so do lots of issues that don’t change votes.

It was September 11, two weeks later, that sent Howard’s voting-intentions figure skywards, but by polling day they had subsided, and the result of fifty-one to forty-nine, while respectable for a government in good economic times asking for a third term, was no landslide.

To answer the question, we need regular and precise estimates of who is likely to win the election. Unfortunately, polls are pretty irregular, and very imprecise (evidence here, anecdote here). But betting markets provide a stable, daily estimate. Here’s the time series for 2001, with the Tampa incident and September 11 attacks marked on the chart.

The chart is from this paper. To my mind, it doesn’t support Brent’s argument that the Howard government were sailing to victory before the Tampa incident. But it does accord with his view that the September 11 attacks were pretty important.